Note: Descriptions are shown in the official language in which they were submitted.
CA 02468120 2004-05-20
ROLLED PAPER HOLDER AND
IMAGE FORMING APPARATUS INCORPORATING THE SAME
BACKGROUND OF THE INVENTION
The present invention relates to a rolled paper holder and a printer
incorporating the same.
A printer is known for forming images (including "character printing")
on a recording medium such as paper (hereinafter, referred as "recording
paper"), using rolled paper as the recording paper. The rolled paper is
advantageous in that it enables a continuous supply of the recording paper for
a long time period.
In the printer of this type, there are a shaft-supporting type and a
throw-in type in connection with the structure of a paper feeding section for
holding the rolled recording paper. In comparison with the shaft-supporting
type, which employs such structure that the supporting shaft is inserted into
the
core hole of the rolled paper, the throw-in type is very convenient since the
operation for setting the rolled recording paper is simply to put the rolled
recording paper into a paper storage space.
A first example of a related-art throw-in type printer 80 (line thermal
printer) will be described below with reference to Figs. 9 through 13.
Incidentally, the overall structure (e.g., a casing body) of the printer 80
will not
be shown.
As shown in Fig. 9, the thermal printer 80 comprises a rolled paper
hoider 71, a thermai recording head 20 disposed on one side (front side of the
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CA 02468120 2004-05-20
M,....
printer) of a paper storage space 72, and a platen roller 30.
The rolled paper holder 71 includes a curved bottom face 71f for
supporting the rolled paper 10 from the lower side, and a right guide face 71d
and a left guide face 71g upright from the bottom face 71f. A recess 71k is
formed at a center part of the bottom face 71f for holding the rolled paper 10
irrespective of the remaining amount thereof.
The right guide face 71 d and the left guicie face 71 g are configured to
face a right end face 10b and a left end face 10c of the rolled paper 10
respectively. The distance between the right guide face 71d and the left
guide face 71g is determined to be slightly larger than the width of the
rolled
paper 10. Therefore, paper 11 drawn out from the outer most periphery of the
rolled paper 10 is guided to a recording section including the platen roller
30
and the thermal recording head 20 while being regulated in position at both
edges thereof by the right guide face 71 d and the left guide face 71 g.
The platen roller 30 is rotatably disposed in parallel with the axial core
of the rolled paper 10. The thermal recording head 20 is disposed in parallel
to and opposed to the platen roller 30. The thermal recording head 20 is
pivotably supported by supporting shafts 20a, 20b provided in parallel with
the
axial core of the platen roller 30. The thermal recording head 20 is urged by
a
not-shown resilient member so that the recording face thereof is pressed
against the platen roller 30 in the direction indicated by an arrow Fl in Fig.
9.
The rolled portion of the rolled paper 10 is held in the paper storage
space 72, and the paper 11 drawn out from the outermost periphery thereof is
clamped between the platen roller 30 and the thermal recording head 20. The
paper 11 is thus trarisporied in a predetermined direction (the direction
CA 02468120 2004-05-20
indicated by an arrow Y) by the rotation of the platen roller 30 when a
not-shown driving source such as a motor is activated.
The printer 80 may be provided with a near-end detector 40 for
detecting that the remaining amount of the rolled paper 10 is coming to an
end.
The near-end detector 40 includes a frame 44, a contact 41, a spring
43, and a switch 42. The contact 41 is pivotably supported by a supporting
member 44a of the frame 44, and the extremity 41 a of the contact 41 is
pressed by resiliency of the spring 43 so as to come into contact with the
left
end face 10c of the rolled paper 10.
The switch 42 is operated in accordance with the pivotal position of
the contact 41. The switch 42 is set to operate in such a manner that the
height of the center of the rolled paper 10 is lowered as the rolled paper 10
is
being consumed, and when the remaining amourit is below a predetermined
amount, the extremity 41 a of the contact enters the rolled paper core hole
10a
by a force of the spring 43 in the direction indicated by an arrow G and a
phantom line shown in Fig. 10. During this operation, the contact 41 is
pivoted and activates the switch 42. The near-E:nd state that the remaining
amount of the rolled paper is below the predetermined amount is detected by
the switch 42.
In such a printer 80, slight variations in parallelism exist between the
bottom face 71f of the rolled paper holder 71 and the platen roller 30, and
variations occur in the outer diameter of the plateri roller 30. When the
paper
11 is drawn out from the rolled paper 10, the amount of paper feeding on the
left and the right in the widthwise direction of the paper 11 differs from
each
other due to such variations. As a result, a component force is generated in
CA 02468120 2004-05-20
the direction of the width of the paper, so that the paper 11 shifts in the
direction of the width at the portion of the outermost periphery of the rolled
paper 10 as shown in Fig. 11.
In such a case, the paper 11 travels in a state where the left end face
10c of the rolled paper 10 is in contact with the left guide face 71g.
Therefore,
the right end face 10b of the rolled paper 10 is brought into contact with the
right guide face 71 d on the other side by the reaction force. In addition,
when
the rolled paper 10 is consumed and the weight is reduced, the influence of
the
frictional force due to the contact between the right end face 10b of the
rolled
paper 10 and the right guide face 71 d increases. Further, when the frictional
force is generated in the hatched section A shown in Fig. 12, the entire
rolled
paper 10 is lifted by the force B drawing out the paper 11.
Specifically, a moment works as a rotational force to lift the rolled
paper 10 in the direction indicated by an arrow C about the position of the
hatched area A as a rotation center (here, the rotation radius is represented
by
L5). Accordingly, the rolled paper 10 is lifted from the bottom face 71f, so
that
the holding state of the rolled paper 10 becomes unstable. Further, the edges
of the paper 11 are strongly brought into contact with the side guide faces 71
d,
71 g of the rolled paper holder 71. As a result, the paper 11 cannot be
accurately fed (skewed travel is occurred), and the edges of the paper 11 are
bent. Further, erroneous detection of the near-end detector 40 would occur
and noise is generated when the lifted rolled paper 10 returns to the original
position thereof and collides with the bottom face 71f.
As noted, a pressing force of the spring 43 always acts on the contact
41. Therefore, the right end face 10b of the rolled paper 10 is strongly
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CA 02468120 2004-05-20
brought into contact with the right guide face 71 d in comparison with the
case
in which the near-end detector 40 is not provided. In other words, frictional
force generated in the hatched area A increases, thereby increasing the
possibility of the above lifting phenomenon.
A problem arises in that while at least a certain level of spring load is
required for the spring 43 in order to secure the accuracy of the near-end
detector 40, a smaller spring load is advantageous for preventing the lifting
phenomenon of the rolled paper 10, and it was very difficult to achieve a
setting which satisfies both conditions.
As shown in Fig. 13, there is a case where the extremity 41 a of the
contact 41 enters the space between the rolled paper 10 and the bottom face
71f when the rolled paper 10 is lifted.
In such a situation, the near-end detector 40 is activated before the
paper reaches the predetermined remaining amount. In addition, it may
cause skewed travel of the paper 11 because the rolled paper 10 is obliquely
held in the paper storage space 72. Consequently, problems such as
misalignment of printing position and bending of the paper edge may occur.
The width of the rolled paper 10 varies from one another due to
manufacturing error or the like. Therefore, the storage space 72 width
between the left and right guide faces 71d, 71g is set to accommodate the
largest possible width of the rolled paper 10. For example, when the smallest
possible width of the rolled paper 10 is accommodated in the storage space 72,
the rolled paper 10 moves in the widthwise direction thereof due to gaps
formed between the side end faces 10b, 10c and the guide faces 71d, 71g.
As a resuit, the positional controi of the paper 11 cannot be stabilized, so
that
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CA 02468120 2004-05-20
deviations of the printing position in the widthwise direction of the paper 11
are
generated.
In order to solve this problem, there is a printer in which one of the
side guide faces of the rolled paper holder 71 is fixed as a reference side,
while the other is provided with a guide member movable in the widthwise
direction of the rolled paper 10. However, the movable guide member has to
be always brought into contact with the side end face of the rolled paper 10
by
the resilient force of a spring member or the like in order to press it
against the
fixed side guide face of the rolled paper holder 71. To attain stable contact
between the rolled paper 10 and the fixed side end face, the resilient force
has
to be stronger than a certain level. As a result, the possibility of the
problems
such as the above-described lifting phenomenon is increased.
A second example of a related-art printer 90 will be described with
reference to Figs. 14 through 16. The members similar to those in the first
related-art printer 80 will be designated by the same reference numerals, and
the repetitive explanation for those will be omitted.
The printer 90 is different from the printer 80 in structure of a rolled
paper holder. Specifically, as shown in Fig. 14, a rolled paper holder 91 is
configured with the distance L1 between front end portions 91 d, 91 g of a
right
guide face and a left guide face adapted to have the same dimension
corresponding to the rolled paper 10 in substantially the same manner as in
the first related-art printer 80. However, the distance L2 between rear end
portions 91e, 91h of the right guide face and the left guide face is adapted
to
be relatively large with respect to the rolled paper 10. In other words, the
distance between the left and right guide faces of the rolled paper holder 91
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CA 02468120 2004-05-20
gradually increases from the front side to the rear side of the printer 90
(from
the right side to the left side of Fig. 14).
On the other hand, as shown in Fig. 15, the distance L4 between
upper end portions of the guide faces of the rolled paper holder 91 is larger
than the distance L3 between lower end portions of the guide faces.
With this arrangement, only the portions of the guide faces that are
closer to the front end and a bottom face 91f of the rolled paper holder 91
(i.e.,
the hatched portion Z in Fig. 16) are brought into contact with the side end
faces 10b, 10c of the rolled paper 10. Hence, the portion where the frictional
forces are generated between the guide faces of the rolled paper holder 91
and the side faces of the rolled paper 10 opposes the lower part of the rolled
paper 10, thereby suppressing the occurrence of the lifting phenomenon.
However, the holding stability with respect to the rolled paper 10 lowers at
the
rear end portions and the upper end portions of ttie guide faces of the rolled
guide holder 91 (i.e., the portions where the distances therebetween are
enlarged). Specifically, there is a problem that the amount of inclination of
the
rolled paper 10 in the widthwise direction thereof increases when the rolled
paper 10 having an outer diameter (thickness) relatively larger than the width
thereof is initially used. Therefore, the rolled recording paper cannot be
held
stably.
It is preferable that the position of installation of one single printer is
not limited to the horizontal face, but may be selected from a plurality of
choices such as the slope face or the vertical wall face in order to increase
flexibility of conditions of installation (the place of installation).
The rolled paper 10 can be stably held when the printer 90 is installed
7
CA 02468120 2004-05-20
on the horizontal face because the distances between the front end portions
and the rear end portions of the guide faces of the rolled paper holder 91 are
substantially coincident with the width of the rolled paper 10. However, if
the
printer 90 is installed at such a position that the ro8led paper 10 is placed
at the
rear part of the rolled paper holder 91, stable holding cannot be attained.
Structures similar to the related-art printers are disclosed in Japanese
Patent Publication No. 2000-44099A, for example.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to provide a throw-in type
rolled paper holder which is capable of preventing the rolled paper from
lifting,
capable of holding the rolled paper stably to thereby prevent noises from
being
generated, capable of preventing malfunction of the near-end detector from
occurring, and capable of preventing the drawn-out paper from being skewed
and bent.
It is also an object of the invention to provide a throw-in type rolled
paper holder capable of stably holding the rolled paper irrespective of the
installation attitude of a printer.
It is also an object of the invention to provide a printer incorporating
such a rolled paper holder.
In order to achieve the above objects, according to the invention,
there is provided a holder for holding a rolled recording medium, comprising:
a pair of side wall members, each of which is opposed to a side end
face of the rolled recording medium to reguiate a position of the roiled
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CA 02468120 2004-05-20
recording medium in a widthwise direction thereof, at least one of the side
wall
members including a first section adapted to be brought into contact with the
side end face, and a second section adapted to avoid contact with the side end
face,
wherein a position of the second section is determined such that an
upper part of the side end face is free from contact with the at least one of
the
side waii members, and wherein a position of the first section is determined
such that a lower part of the side end face is brought into contact with the
first
section.
Preferably, the second section is a recess formed on the at least one
of the side wall members.
Preferably, the holder further comprises a bottom wall member
connecting the side wall members and formed with at least one recess for
holding the rolled recording medium at a predetermined position.
Here, it is preferable that the at least one recess includes a first
recess for holding the rolled recording medium at a first predetermined
position
when the holder is horizontally installed, and a sE:cond recess for holding
the
recording medium at a second predetermined position when the holder is
vertically installed.
Preferably, the holder further comprises a detector provided on one of
the side wall members, the detector comprising a contact member abutted
against one of the side end faces of the rolled recording medium such that a
contact condition is changed when a diameter of the roiled recording medium
becomes a predetermined value or less. Here, the first section and the
second section are provided on the other of the side wafl members.
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CA 02468120 2004-05-20
Preferably, one of the side wall members is movable in the widthwise
direction of the rolled recording medium so as to resiliently press the rolled
recording medium against the other of the side wall members.
According to the invention, there is also provided an image forming
apparatus comprising an image forming section, which performs an image
forming operation with respect to a recording medium drawn out from the rolled
recording member held in the above holder.
According to the invention, there is also provided a recording medium
holder for holding a rolled recording medium, where the recording medium
holder comprises a pair of sidewalls sufficiently spaced to receive the rolled
recording medium, with at least one of the sidewalls including a recessed
portion therein defining a non-contact area. At least one sidewall is
structured
such that when a size of the rolled recording medium is below a predetermined
diameter, a portion of the rolled recording medium is disposed adjacent the
recessed non-contact area.
Also according to the invention, there is provided a paper holder for
holding a paper roll, the paper holder comprising:
a bottom wall member shaped to support the paper roll, and
a pair of sidewalls extending upward from the bottom wall member,
the sidewalls being sufficiently spaced to receive the paper roll, wherein at
least one of the sidewalls comprises structure for avoiding contact with a
side
end face of the paper roll regardless of an orientation of the paper holder
and
depending on a size of the paper roll.
A printer including a print head and a plciten roller disposed adjacent
t, ie print head and incorporating the paper hoider of the invention is also
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CA 02468120 2007-01-02
provided.
With the above configurations, the rolled recording medium held in the holder
can be rotated with less force, so that the recording medium subjected to the
image
forming operation can be drawn out from the rolled recording medium smoothly
and
stably. Further, since the distance between the side wall members are suitably
determined relative to the width of the rolled recording member, loading the
rolled
recording medium is easy, and noises due to the play of the rolled recording
medium can be prevented by gaps between the rolled recording medium and the
side wall members. Further, skewed travel and edge bending of the recording
medium can be avoided.
In addition, since the contact load of the contact member of the detector is
allowed to be increased, the design flexibility of the detector and the
holding stability
with respect to the rolled recording medium can be increased.
In another aspect, the present invention provides a holder for holding a
rolled
recording medium, the holder comprising: a pair of side wall members, each of
which
is opposed to a side end face of the rolled recording medium to regulate a
position of
the rolled recording medium in a widthwise direction thereof; a bottom wall
member
connecting the side wall members and supporting the rolled recording medium on
a
surface thereof regardless of a diameter thereof; a first section, provided on
an inner
surface of at least one of the side wall members, and adapted to come in
contact with
a lower part of a side end face of the recording medium regardless of the
diameter
thereof; and a second section, provided on the inner face of the at least one
of the
side wall members and adapted to avoid contact with at least a part of an
upper part
of the side end face of the recording medium regardless of the diameter
thereof.
In another aspect, the present invention provides a recording medium holder
for holding a rolled recording medium, the recording medium holder comprising:
a pair
of sidewalls sufficiently spaced to receive the rolled recording medium, at
least one of
the sidewalls including a recessed portion therein defining a non-contact
area; and a
bottom wall member connecting the side wall members and supporting the rolled
recording medium on a surface thereof regardless of a diameter thereof,
wherein at
least one sidewall is structured such that when a size of the rolled recording
medium is
below a predetermined diameter, a portion of the rolled recording medium is
disposed
11
CA 02468120 2007-01-02
adjacent the recessed non-contact area.
In another aspect, the present invention provides a paper holder for holding a
paper roll, the paper holder comprising: a bottom wall member shaped to
support the
paper roll on a surface thereof regardless of a diameter thereof; and a pair
of sidewalls
extending upward from the bottom wall member, the sidewalls being sufficiently
spaced
to receive the paper roll, wherein at least one of the sidewalls comprises
means for
avoiding contact with a side end face of the paper roll regardless of an
orientation of the
paper holder and depending on a size of the paper roll.
In another aspect, the present invention provides a printer comprising: a
print
head; a platen roller disposed adjacent the print head; and a paper holder for
holding a
paper roll, the paper holder including, a bottom wall member shaped to support
the
paper roll on a surface thereof regardless of a diameter thereof, and a pair
of sidewalls
extending upward from the bottom wall member, the sidewalls being sufficiently
spaced
to receive the paper roll, wherein at least one of the sidewalls comprises
means for
avoiding contact with a side end face of the paper roll regardless of an
orientation of the
printer and depending on a size of the paper roll, wherein paper is delivered
to the print
head and platen roller from the paper holder.
Furthermore, the above advantages can be obtained irrespective of the
installation attitude of the holder. There can be provided an image forming
apparatus adapted for various installation requirements.
BRIEF DESCRIPTION OF THE DRAWINGS
The above objects and advantages of the present invention will become
more apparent by describing in detail preferred exemplary embodiments thereof
with reference to the accompanying drawings, wherein:
Fig. 1 is a perspective view of a portion of a printer according to a first
embodiment of the invention;
11a
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Fig. 2 is a perspective view of a rolled paper holder in the printer of
Fig. 1;
Fig. 3 is a section view taken along a line I11-111 in Fig. 1, showing a
state that the remaining amount of the rolled paper is large;
Fig. 4 is a section view taken along the line lil-III in Fig. 1, showing a
state that the remaining amount of the rolled paper is small;
Fig. 5 is a section view taken along a line V-V in Fig. 1;
Fig. 6 is a section view taken along the line 111-111 in Fig. 1, showing a
state that the printer is vertically installed;
Fig. 7 is a section view of a portion of a printer according to a second
embodiment of the invention;
Fig. 8 is a perspective view of a rolled paper holder in the printer of
Fig. 7;
Fig. 9 is a perspective view of a portion of a first related-art printer;
Fig. 10 is a section view taken along a line X-X in Fig. 9;
Fig. 11 is a plan view for explaining a problematic condition occurred
in the printer of Fig. 8;
Fig. 12 is a section view for explaining a problematic condition
occurred in the printer of Fig. 8;
Fig. 13 is a section view for explaining a problematic condition
occurred in the printer of Fig. 8;
Fig. 14 is a perspective view of a portion of a second related-art
printer;
Fig. 15 is a section view taken along a line XV-XV in Fig. 14; and
Fig. 16 is a section view for explainingl a problematic condition
19
CA 02468120 2004-05-20
occurred in the printer of Fig. 14.
DETAILED DESCRIPTION OF THE INVENTION
Preferred embodiments of the invention will be described below in
detail with reference to the accompanying drawings.
A line thermal printer 70 (hereinafter, simply referred as "printer")
which is a first embodiment of the invention will be described with reference
to
Figs. 1 through 6.
Fig. 1 to Fig. 6 are drawings showing a first embodiment of the
present invention. The members similar to those in the first related-art
printer
80 will be designated by the same reference numerals, and the repetitive
explanation for those wiii be omitted.
As shown in Fig. 1, the printer 70 comprises a rolled paper holder 1, a
thermal recording head 20 disposed on one side (front side of the printer) of
a
paper storage space 2 of the rolled paper holder 1, a platen roller 30, and a
near-end detector 40 for detecting that the remaining amount of the rolled
paper 10 is coming to an end.
The rolled paper holder 1 includes a curved bottom face 1f for
supporting the rolled paper 10 from the lower side, and a right guide face 1 d
and a left guide face 1 g upright from the bottom face 1 f. A recess 1 k is
formed at a center part of the bottom face 1f for holding the rolled paper 10
irrespective of the remaining amount thereof (see Figs. 3 and 4).
The right guide face 1 d and the left guic9e face 1 g are configured to
face a right end face 10b and the ieft end face 10c of the roiied paper 10
1-1
CA 02468120 2004-05-20
respectively. The distance between the right guide face 1 d and the left guide
face 1g is determined to be slightly larger than the width of the rolled paper
10.
Therefore, paper 11 drawn out from the outer niost periphery of the rolled
paper 10 is guided to a recording section including the platen roller 30 and
the
thermal recording head 20 while being regulated in position at both edges
thereof by the right guide face 1 d and the left guide face 1 g.
In this embodiment, as shown in Fig. 2, the right guide face 1 d is
formed with a recess 1 c at a substantially central portion thereof. The
recess
1 c has a truncated triangular pyramid shape in which a central bottom part 1
m
is continued from the right guide face 1 d via gentle slopes Is. Due to the
existence of the recess 1 c, at least a part of the upper part of the rolled
paper
10 (i.e., the part above the core hole 10a) is always free from contact with
the
right guide face 1 d. On the other hand, the lower part (i.e., the part below
the
core hole 10a) is always brought into contact with a guiding portion 1 p of
the
right guide face 1 d irrespective of the diameter of the rolled paper 10 (see
Figs.
3 and 4).
More specifically, when the diameter of the rolled paper 10 is
relatively large as shown in Figs. 1 and 3, the side end face 10b of the
rolled
paper 10 is supported by a guiding portion 1t and the guiding portion 1 p. On
the other hand, when the diameter of the rolled paper 10 is relatively small
as
shown in Figs. 4 and 5, the side end face 10b is supported by only the guiding
portion 1 p. That is, the guiding portion 1 p is always opposed to a portion
of
the rolled paper 10 where the paper 11 is drawn out with the rolled paper held
by edges 12 of the recess 1 k as shown in Figs. 3 and 4. To establish this
positional relationship, the recess 1 c is situated closer to the rear end of
the
14
CA 02468120 2004-05-20
rolled paper holder I relative to the recess 1 k as shown in Fig. 2.
Therefore, when the diameter of the rolled paper 10 becomes small,
the upper part of the rolled paper 10 (the hatched section A in Fig. 12) is
completely free from contact with the right guide face 1d. The contact
between the rolled paper 10 and the right guide face is rather established
only
at the hatched section D in Fig. 4. As a result, a distance L6 between a
portion to be an undesired rotation center of the rolled paper 10 (the
substantially center portion of the hatched section D) and the drawn-out
portion
of the paper 11 is sufficiently smaller than the distance L5 shown in Fig. 12.
In comparison with the related-art printers, a moment lifting the roller paper
10
becomes considerably small with regard to the weight of the rolled paper 10.
Accordingly, the lifting phenomenon can be prevented even if the diameter
(weight) of the rolled paper 10 becomes small.
In a case where the printer 70 is installed so as to lie along a vertical
wall face 100 as shown in Fig. 6, the rolled paper 10 is supported by holding
edges 13 of supporting projections 1 a, lb provided on the rear side of the
rolled paper holder 1 and the curved portion of the bottom face 1f. In other
words, in the state of the printer installed as shown in Fig. 6, a recess 2k
is
formed between the holding edges 13.
It is also necessary to dispose the near-end detector 40 (shown by a
phantom line in Fig. 6) corresponding to the recess 2k. Therefore, the
mounting angle is about 90 degrees different from the case shown in Fig. 4,
and the mounting direction and position are determined corresponding to the
level of the core hole 10a when the rolled paper 10 is consumed to a
predetermined amount.
1.r,
CA 02468120 2004-05-20
In this case, when the diameter of the rolled paper 10 is relatively
large, the side end face 10b of the rolled paper '10 is supported by a guiding
portion 1 t and a guiding portion lq. On the other hand, when the diameter of
the rolled paper 10 is relatively small as shown in Fig. 6, the side end face
10b
is supported by only the guiding portion 1 q. That is, the guiding portion 1 q
is
always opposed to a portion of the rolled paper 10 where the paper 11 is
drawn out in a state that the rolled paper is held by edges 13 of the recess
2k.
As in the case where the printer 70 is horizontally installed as shown
in Fig. 4, the moment lifting the rolled paper 10 is suppressed, so that the
paper 11 can be fed smoothly.
In this embodiment, the position of the recess 1 c is so determined
that an upper end of the side end face 10b of the rolled paper 10 opposes an
upper end of the recess 1 c when the diameter of the rolled paper 10 becomes
two thirds of the initial diameter thereof when the printer 70 is horizontally
placed as shown in Fig. 4. It should be noted that the rolled paper 10 which
is
relatively small in width is lighter than the rolled paper 10 having the
larger
width even when the outer diameter is the same. In addition, the width
supported by the bottom face 1f is relatively smaller than the outer diameter
of
the rolled paper 10. In such a case, the entire rolled paper 10 tends to be
inclined in the widthwise direction thereof, so that the lifting phenomenon
due
to generation of the moment tends to occur. In view of the above, it is
preferable to determine the position and shape of the recess 1 c taking due
account of the width and the weight of the rolled paper 10 relative to the
outer
diameter thereof, the pressing force of the contact 41 of the near-end
detector
40, and the friction coefficient of the portion which comes in contact with
the
16
CA 02468120 2004-05-20
end face 10b of the rolled paper 10, which is determined by the material of
the
rolled paper holder 1.
Generally, in order to stabilize the movement of the contact 41 when
detection is made by the near-end detector 40, it is necessary to allow the
contact 41 to come into contact with the end face 10c of the rolled paper 10
by
at least a certain pressing force. In this embodiment, since the rolled paper
can be held in a stable manner even when a force is exerted from the end
face 10c, the spring load of the near-end detector 40 can be increased, and
hence the design flexibility of the near-end detector 40 is advantageously
10 improved.
Next, a printer 170 according to a second embodiment of the
invention will be described with reference to Figs. 7 and 8. In these figures,
the thermal recording head 20 and the platen roller 30 are omitted. The
members similar to those in the first ernbodiment will be designated by the
same reference numerals, and the repetitive explanation for those will be
omitted.
In this embodiment, a rolled paper holder 91 includes a right guide
face 91 d fixed with respect to the bottom face 1 f for guiding the end face
10b
of the rolled paper 10, and a holding face 50a which is a movable guide face
for pressing the rolled paper 10 toward the right guide face 91 d with
resilient
forces generated by springs 51.
As shown in Fig. 7, a holding plate 50 having the holding face 50a is
supported by a plurality of guide shafts 50c penetrating a left wall 60 so as
to
be capable of sliding in the widthwise direction of the rolled paper 10 (the
laterai direction in this figure). The springs 51 are provided between the
17
CA 02468120 2004-05-20
holding plate 50 and the left side wall 60 while being wound around the guide
shafts 50c. Therefore, the rolled paper 10 is always kept stable at the
reference position at which the rolled paper is brciught into press contact
with
the right guide face 91 d.
in.this embodiment, the above-described guiding portions 9 p, lq, 1 t
are defined by a recess 50b formed on the holding plate 50 and the recess 1 c
formed on the right guide face 91 d. The recess 50b is provided so as to
oppose to the recess 1 c.
When the printer 170 is installed horizontally as shown in Fig. 7, when the
diameter of the rolled paper 10 is relatively large, the side end face 10b of
the
rolled paper 10 is supported by the guiding portions lq, It of the right guide
face 91 d, while the side end face 10c of the rolled paper 10 is supported by
the
guiding portions 1 q, 1 t of the holding face 50a. On the other hand, when the
.
diameter of the rolled paper 10 is relatively small, the side end face 10b is
supported by only the guiding portion 1 q of the right guide face 91 d, while
the
side end face 10c of the rolled paper 10 is supported by only the guiding
portion 1 q of the holding face 50a. That is, the guiding portions 1 q are
always
opposed to a portion of the rolled paper 10 where the paper 11 is drawn out.
Accordingly, also in this embodiment, the moment lifting the rolled paper 10
is
reduced, so that the paper 11 can be fed smoothly.
In the first embodiment, although the recess 1 c defining the guiding
portions 1 p, 1 q, 1 t is formed on only the side guide face 1 d of the rolled
paper
holder 1, the recess 1 c may be formed the other side guide face 1 g as in the
second embodiment.
In ti ~e above embodiments, although the printer is provided with the
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CA 02468120 2004-05-20
mechanical-type near-end detector 40 having the contact 41 to be entered into
the core hole 10a of the rolled paper 10, the contact 41 may be configured
such that the contact 41 urging the side end face 10b of the rolled paper 10
proceeds so as to slide on the outer periphery of the rolled paper 10 when the
size of the rolled paper 10 is below a predetermined diameter. Alternatively,
it
may be replaced with an optical-type near-end detector, or may be omitted.
The shape of the recess 1 c is not limited as configured in the above
embodiments. The contour of the recess 1c may be arbitrarily determined
(e.g., polygonal, circular, oval). The edges connecting the respective peaks
of the contour of the recess 1 c may be curved. Ribs for supporting the side
end faces of the rolled paper 10 may be protruded from the side guide faces of
the rolled paper holder so as to define a non-contact part corresponding to
the
above recesses. The recess 1 c may be a through hole.
In the above embodiments, although two recesses 1 k, 2k for holding
the rolled paper 10 are formed on the bottom face 1 f, additional recesses may
be included.
In the above embodiments, the invention is applied to a printer
employing a line thermal recording head. The invention may alternatively be
applied to an apparatus which employs an impact-dot type recording head or
an ink jet recording head, in which the rolled recording medium is loaded by
the throw-in system.
While the invention has been described iin connection with what is
presently considered to be the most practical and preferred embodiments, it is
to be understood that the invention is not to be limited to the disclosed
embodiments, but on the contrary, is intended to cover various modifications
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CA 02468120 2004-05-20
and equivalent arrangements included within the spirit and scope of the
appended claims.
